It has been known for many years to provide photographic elements, including both films and papers, with antistatic protection. Such protection is very important since the accumulation of static electrical charges on photographic elements is a very serious problem in the photographic art. These charges arise from a variety of factors during the manufacture, handling and use of photographic elements. For example, they can occur on sensitizing equipment and on slitting and spooling equipment, and can arise when the paper or film is unwound from a roll or as a result of contact with transport rollers. The generation of static is affected by the conductivity and moisture content of the photographic material and by the atmospheric conditions under which the material is handled. The degree to which protection against the adverse effects of static is needed is dependent on the nature of the particular photographic element. Thus, elements utilizing high speed emulsions have a particularly acute need for antistatic protection. Accumulation of static charges can cause irregular fog patterns in a photographic emulsion layer, and this is an especially severe problem with high speed emulsions. Static charges are also undesirable because they attract dirt to the photographic element and this can cause repellency spots, desensitization, fog and physical defects.
To overcome the adverse effects resulting from accumulation of static electrical charges, it is conventional practice to include an antistatic layer in photographic elements. Typically, such antistatic layers are composed of materials which dissipate the electrical charge by providing a conducting surface. A very wide variety of antistatic agents are known for use in antistatic layers of photographic elements. For example, U.S. Pat. No. 2,649,374 describes a photographic film comprising an antistatic layer in which the antistatic agent is the sodium salt of a condensation product of formaldehyde and naphthalene sulfonic acid. An antistatic layer comprising an alkali metal salt of a copolymer of styrene and styrylundecanoic acid is disclosed in U.S. Pat. No. 3,033,679. Photographic films having an antistatic layer containing a metal halide, such as sodium chloride or potassium chloride, as the conducting material, a polyvinyl alcohol binder, a hardener, and a matting agent are described in U.S. Pat. No. 3,437,484. In U.S. Pat. No. 3,525,621, the antistatic layer is comprised of colloidal silica and an organic antistatic agent, such as an alkali metal salt of an alkylaryl polyether sulfonate, an alkali metal salt of an arylsulfonic acid, or an alkali metal salt of a polymeric carboxylic acid. Use in an antistatic layer of a combination of an anionic film forming polyelectrolyte, colloidal silica and a polyalkylene oxide is disclosed in U.S. Pat. No. 3,630,740. In U.S. Pat. No. 3,655,386, the surface conductivity of photographic film is improved by coating it with an aqueous alcohol solution of sodium cellulose sulfate. In U.S. Pat. No. 3,681,070, an antistatic layer is described in which the antistatic agent is a copolymer of styrene and styrene sulfonic acid. U.S. Pat. No. 4,542,095 describes antistatic compositions comprising a binder and a nonionic surface-active polymer having polymerized alkylene oxide monomers and an alkali metal salt. In U.S. Pat. No. 4,623,594, an antistatic layer is formed by curing a composition comprising an electron radiation curable prepolymer and an electron radiation reactive antistatic agent that is soluble in the prepolymer.
It is known to prepare an antistatic layer from a composition comprising a salt dissolved in a poly(ethylene oxide), as described, for example, in U.S. Pat. Nos. 4,582,781 and 4,610,955. These compositions are compatible with photographic materials and very effective in reducing surface resistivity and thereby providing protection against static. However, they are seriously lacking in the abrasion-resistance and scratch-resistance that are often needed with antistatic layers utilized in the photographic arts.
It is toward the objective of providing a composition that is capable of forming an abrasion-resistant antistatic layer, meeting the stringent requirements of the photographic field, that the present invention is directed.